This study is a retrospective cohort study, performed by following up on subjects from a series of non-randomized clinical trials performed during 1965-1978 in Iowa, for the purpose of determining if exposure to soy formula in infancy may be associated with adverse outcomes in early adulthood. Researchers are locating the majority of the subjects included in the original exposure cohorts (soy formula and cow milk-based formula) from the clinical trials, and to ask for their cooperation in a new study which will be asking for information about their medical histories from infancy through the present time. The incidence and distributions of selected outcomes will then be compared among these exposure groups. This project is associated with a follow-up questionnaire study of babies who received different kinds of infant formula 20-40 years ago. This study will be supported by the manufacturers of infant formula if enough of this cohort can still be located and recruited to participate. Only one such cohort of sufficient size was ever described in the literature with enough identifying information to make recruitment feasible. This is the group of babies studied at the University of Iowa by Drs. Samuel Fomon and Ekhard Ziegler. It is to be the government~s role to support the organization of the files, location of the research subjects, and the initial approach to determine their willingness to respond to a questionnaire study. The major advantage to the government of this sole- source contract is that all of the cost of the follow-up study of a soy- fed infants which the ENG Branch thinks public welfare demands will be borne by the formula manufacturers. Clearly, no prospective 20-year follow-up study on this subject is feasible; the retrospective study is the next-best alternative. This is the only group with adequate records known to be available. Moreover, this is the group on which the formula manufacturers have elected to support research.